My tape measure says for inside dimensions add 3 1/4" to the measurement. My old eyes have a hard time reading exactly where to pull the measurement and nobody wants to add 13/16ths to 1/4". There has to be a better way.

The 1 2 plus 4 block measures one inch by two inches by 4 inches with 1/4" markings on several sides. it fits over many tape measures to give easy to read ID measurements with easy math adding 4" to the measurement displayed on the tape.